Battery pack

ABSTRACT

A battery pack includes a plurality of battery modules including a plurality of cells  100  aligned and accommodated in a case, wherein a battery assembly  200  in which the plurality of cells  100  are aligned in a row is used as a unit, and the multiple ones of the battery assembly  200  are aligned in each battery module. The battery modules are a first battery module  300  in which the plurality of battery assemblies  200  are aligned in parallel and second battery modules  400 A,  400 B in which the plurality of battery assemblies  200  are aligned in series, and the first battery module  300  and the second battery modules  400 A,  400 B are combined with each other to form the battery pack.

RELATED APPLICATIONS

This application is the U.S. National Phase under 35 U.S.C. §371 ofInternational Application No. PCT/JP2010/006627, filed on Nov. 11, 2010,which in turn claims the benefit of Japanese Application No.2010-038655, filed on Feb. 24, 2010, the disclosures of whichApplications are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to battery packs including a plurality ofbattery modules each including a plurality of batteries.

BACKGROUND ART

Battery packs including a plurality of batteries accommodated in a caseto allow an output of a predetermined voltage and capacitance are widelyused as power sources of various devices, vehicles, etc. Specifically,the technique of forming modules of battery assemblies obtained byconnecting general-purpose batteries in parallel and/or in series tooutput a predetermined voltage and capacitance, and combining thebattery modules together to be applicable to various applications isbeginning to be used. This module forming technique can reduce the sizeand weight of the battery modules themselves by increasing theperformance of batteries accommodated in the battery modules. Thus, thismodule forming technique has various advantages, an example of which isthat workability can be improved in assembling a battery pack, and theflexibility in mounting the battery module in areas of limited space,such as a vehicle, can be increased.

However, the performance of the batteries included in each batteryassembly is not necessarily uniform. Therefore, for example, duringdischarge, the current capacity of the battery assembly is limited by abattery having a minimum capacity, and during charge, recharging thewhole battery assembly is limited by the battery having the minimumcapacity. Thus, when the battery assembly is charged and dischargedbeyond such limits, problems such as a reduction in cycle life of thebattery assembly may arise due to deterioration of the battery havingthe minimum capacity.

As a method to solve such problems, Patent Document 1 describes that ina battery assembly including a plurality of batteries connected to eachother in parallel and/or in series, adjacent batteries are connected toeach other in a complex manner to configure a network. When such anetwork is configured, batteries having non-uniform properties areautomatically equilibrated, so that it is possible to reduce performancedegradation of a certain battery, as a result of which the cycle life ofthe battery assembly can be extended.

CITATION LIST Patent Document

-   PATENT DOCUMENT 1: Japanese Translation of PCT International    Application No. 2002-533042

SUMMARY OF THE INVENTION Technical Problem

As described above, forming modules of battery assemblies andaccordingly combining these battery modules with each other to fit intoa limited space in, for example, a vehicle allow flexible mounting of abattery pack capable of outputting a predetermined voltage andcapacitance.

For example, when a battery module is formed by two-dimensionallyaligning cylindrical batteries, the external size of the battery moduledepends on the number of rows and columns of the two-dimensionallyaligned cylindrical batteries. With reference to the external size, thenumber of battery modules to be aligned and the disposition orientation(vertical disposition or horizontal disposition) of the battery modulesare varied so that a battery pack in which the plurality of batterymodules are combined with each other fits to the size of a limited spaceand can be mounted in the limited space.

However, the external size of the battery module is limited by theheight of the cylindrical batteries, and the number of rows and columnsof the two-dimensionally aligned cylindrical batteries. Thus, there isthe case where the battery pack cannot be mounted in a narrow space evenwhen the number of the battery modules to be aligned, or the dispositionorientation of the battery modules are varied. It cannot be said thatthe flexibility in mounting the battery modules in a limited space isnecessarily sufficient.

In view of the above-described points, the present invention has beendevised. It is a primary objective of the present invention to provide abattery pack including a plurality of battery modules, wherein theflexibility in mounting the battery modules in a limited space isimproved.

Solution to the Problem

In the present invention, a battery assembly including a plurality ofcells aligned in a row is used as a unit, a first battery module inwhich multiple ones of the battery assembly are aligned in parallel anda second battery module in which multiple ones of the battery assemblyare aligned in series are prepared, and these two types of batterymodules are combined with each other to form a battery pack.

The minimum width of the external size of the second battery moduleincluding the plurality of battery assemblies aligned in series matchesthe minimum width of the cells included in the battery assemblies. Bycontrast, the minimum width of the external size of the first batterymodule including the plurality of battery assemblies aligned in parallelvaries depending on the number of the battery assemblies aligned inparallel, but the minimum width is at least the product of the minimumwidth of the cells and the number of the battery assemblies. Therefore,it is possible to widen the difference between the minimum widths of theexternal sizes of the first battery module and the second batterymodule. Thus, mounting the first battery module in a wide space, and thesecond battery module in a narrow space can increase the flexibility inmounting the battery pack in a limited space. Moreover, the firstbattery module and the second battery module are both formed by using abattery assembly including a plurality of cells aligned in a row as aunit, so that it is possible to easily form the battery modules.

That is, a battery pack according to the present invention includes: aplurality of battery modules each including a plurality of cells alignedand accommodated in a case, wherein a battery assembly including aplurality of cells aligned in a row is used as a unit, and each batterymodule is formed by aligning multiple ones of the battery assembly, thebattery modules include a first battery module in which the batteryassemblies are aligned in parallel, and a second battery module in whichthe battery assemblies are aligned in series, and the first batterymodule and the second battery module are combined with each other toform the battery pack.

Here, it is preferable in the battery pack that the plurality of cellsaligned in a row be electrically connected to each other in parallel.With this configuration, in the battery pack which is formed bycombining the first battery module and the second battery module whichare formed by using the battery assembly as a unit, current supply fromthe battery pack can be ensured even in case of a failure of one cellincluded in the battery assembly.

Moreover, each battery assembly preferably includes an electrodeterminal as a positive electrode, and an electrode terminal as anegative electrode, and a signal terminal via which a signal forcontrolling charge and discharge of the cells is input and output. Withthis configuration, battery modules including battery assemblies areeasily electrically connected to each other, and charge and discharge ofthe battery modules are easily controlled.

Moreover, each cell has an opening portion (safety valve) through whichgas generated in the cell is exhausted to the outside of the cell, andeach battery assembly further includes an exhaust duct in communicationwith the opening portion of each cell. With this configuration, evenwhen heat is abnormally generated in one of the cells included in thebattery assembly, and a safety valve is activated to exhausthigh-temperature gas to the outside of the cell, the high-temperaturegas is not exposed to the cells in the periphery of the cell from whichthe gas is exhausted, and the high-temperature gas can be exhausted tothe outside of the battery assembly via the exhaust duct. As a result,even in case of a failure of one of the cells included in the batteryassembly, the failure does not influence other normal cells, so that itis possible to form a highly safe battery module.

Advantages of the Invention

According to the present invention, a battery pack includes two types ofbattery modules having different minimum widths of external sizes, andthe two types of the battery modules are formed by using a batteryassembly including a plurality of cells aligned in a row as a unit, sothat it is possible to easily form a battery pack having highflexibility in mounting in a limited space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating aconfiguration of a cell used for a battery module of an embodiment ofthe present invention.

FIG. 2 is an exploded perspective view schematically illustrating aconfiguration of a battery assembly of the embodiment of the presentinvention.

FIG. 3A is a perspective view of the battery assembly of the embodimentof the present invention. FIG. 3B is a cross-sectional view of thebattery assembly. FIG. 3C is an enlarged view of part A of FIG. 3B.

FIGS. 4A-4E are exploded perspective views schematically illustrating aconfiguration of a first battery module of the embodiment of the presentinvention.

FIG. 5 is a perspective view of the first battery module of theembodiment of the present invention.

FIGS. 6A-6E are exploded perspective views schematically illustrating aconfiguration of a second battery module of an embodiment of the presentinvention.

FIG. 7 is a perspective view of the second battery module of theembodiment of the present invention.

FIGS. 8A-8D are exploded perspective views schematically illustrating aconfiguration of a second battery module of another embodiment.

FIG. 9 is a perspective view of the second battery module of the anotherembodiment.

FIG. 10 is a view illustrating an example in which a battery packincluding a plurality of battery modules is mounted on a vehicle.

FIGS. 11A, 11B are perspective views illustrating an example combinationof the first battery module and the second battery module.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail belowwith reference to the drawings. The present invention is not limited tothe following embodiments. The embodiment can be modified withoutdeviating from the effective scope of the present invention. Theembodiment can be combined with other embodiments.

FIG. 1 is a cross-sectional view schematically illustrating aconfiguration of a battery (hereinafter referred to as a “cell”) 100used for a battery module of an embodiment of the present invention.Note that a battery pack of the present invention is configured as a setof battery modules, wherein a battery assembly in which multiple ones ofthe cell 100 are aligned in a row is used as a unit, and each batterymodule is formed by aligning multiple ones of the battery assembly.

The cell 100 included in the battery assembly of the present inventioncan be, for example, a cylindrical lithium ion secondary battery asillustrated in FIG. 1. The lithium ion secondary battery may be ageneral-purpose battery used as a power source of portable electronicdevices such as laptop computers. In this case, a high-performancegeneral-purpose battery can be used as a cell of a battery module, andthus the performance of the battery module can be easily increased, andthe cost of the battery module can be easily reduced. Moreover, the cell100 includes a safety mechanism to release gas to the outside of thecell when the pressure in the cell increases due to the occurrence of,for example, an internal short circuit. A specific configuration of thecell 100 will be described below with reference to FIG. 1.

As illustrated in FIG. 1, an electrode group 4 formed by winding apositive electrode 1 and a negative electrode 2 with a separator 3interposed between the positive electrode 1 and the negative electrode 2is accommodated in a battery case 7 with a nonaqueous electrolyte.Insulating plates 9, 10 are provided above and under the electrode group4, respectively. The positive electrode 1 is connected to a filter 12via a positive electrode lead 5. The negative electrode 2 is connectedto a bottom section of the battery case 7 via a negative electrode lead6, where the bottom section of the battery case 7 also serves as anegative electrode terminal.

The filter 12 is connected to an inner cap 13. A protruding section ofthe inner cap 13 is connected to a valve 14 made of metal. Moreover, thevalve 14 is connected to a terminal board 8 (an electrode section of thepositive electrode) also serving as a positive electrode terminal. Theterminal board 8, the valve 14, the inner cap 13, and the filter 12altogether seal an opening of the battery case 7 via a gasket 11.

When an internal short circuit, or the like occurs in the cell 100, andthe pressure in the cell 100 increases, the valve 14 expands to theterminal board 8, and when the connection between the inner cap 13 andthe valve 14 is released, a current path is shutdown. When the pressurein the cell 100 further increases, the valve 14 breaks. Thus, gasgenerated in the cell 100 is exhausted to the outside via a through hole12 a of the filter 12, a through hole 13 a of the inner cap 13, a gap ofthe valve 14, and an opening portion 8 a of the terminal board 8.

Note that a safety mechanism to exhaust gas generated in the cell 100 tothe outside may be, but not limited to, the structure illustrated inFIG. 1.

FIG. 2 is an exploded perspective view schematically illustrating aconfiguration of a battery assembly 200 of the present embodiment. FIG.3A is a perspective view of the battery assembly 200. FIG. 3B is across-sectional view of the battery assembly 200. FIG. 3C is an enlargedview of part A of FIG. 3B.

As illustrated in FIG. 2, the plurality of cells (cylindrical batteries)(in the figure, six cells) 100 are aligned in a row, and areaccommodated in a case 30 to form the battery assembly 200 asillustrated in FIG. 3A. Here, the positive electrode terminals 8 of thecells 100 are aligned in a same direction, and the plurality of cells100 aligned in a row are electrically connected to each other inparallel. With this configuration, in the battery pack formed bycombining the battery modules in each of which the battery assembly 200is used as a unit, current supply from the battery pack can be ensuredeven in case of a failure of one of the cells 100 included in thebattery assembly 200.

Specifically, as illustrated in FIG. 2, a positive electrode connectionplate 21 and a negative electrode connection plate 22 are formed on asurface of a flat plate 20. As illustrated in FIG. 3C, the positiveelectrode connection plate 21 is connected to the positive electrodeterminals 8 of the cells 100 via openings 20 a formed in the flat plate20. Moreover, the negative electrode terminals (the bottom sections ofthe battery cases 7) of the cells 100 are connected to each other via anegative electrode bus bar 23, and are connected to the negativeelectrode connection plates 22, 22 b formed on the flat plate 20 viaconduction sections 24, 24 a extending from a part of the negativeelectrode bus bar 23. With this configuration, the cells 100 areelectrically connected to each other in parallel via the positiveelectrode connection plate 21 and the negative electrode connectionplate 22 formed on the flat plate 20.

Moreover, as illustrated in FIG. 3C, the flat plate 20 is placed inclose contact with an end section of each cell 100 (in the presentembodiment, at a side close to the positive electrode terminal 8). Asillustrated in FIG. 3B, the opening portions 8 a of the cells 100 are incommunication with an exhaust duct 50 provided in a space between theflat plate 20 and a lid 40 via openings 21 b of the positive electrodeconnection plate 21. With this configuration, high-temperature gasexhausted via the opening portion 8 a of the cell 100 is exhausted tothe exhaust duct 50 via the opening 20 a formed in the flat plate 20.Moreover, the exhaust duct 50 is partitioned in a substantially sealedstate with respect to the plurality of cells 100. Thus, thehigh-temperature gas exhausted to the exhaust duct 50 is not exposed tothe cells 100 in the periphery of the cell 100 which exhausts thehigh-temperature gas, and can be released via the exhaust duct 50 to theoutside of the battery assembly 200 from an outlet 40 a formed in thelid 40.

Moreover, as illustrated in FIG. 3A, an end section of the flat plate 20protrudes from the outlet 40 a of the lid 40 to the outside, and anelectrode terminal 21 a as a positive electrode and an electrodeterminal 22 a as a negative electrode are exposed to the outside, wherethe electrode terminal 21 a is provided at an end section of thepositive electrode connection plate 21, and the electrode terminal 22 ais provided at an end section of the negative electrode connection plate22. With this configuration, the battery assemblies 200 can be easilyelectrically connected to each other. Note that the flat plate 20 may bea circuit board on which the electrode terminals 21 a, 22 a as thepositive electrode and the negative electrode, and a signal terminal(not shown) via which a signal for controlling charge and discharge ofthe cells 100 is input and output are formed.

Here, in the battery assembly 200 of the present invention, theplurality of cells 100 may be aligned in a row, but the direction of thepositive electrode terminals 8 of the cells 100 and the electricalrelationship of the connection between the cells 100 are notparticularly limited. For example, the cells 100 adjacent to each othermay be aligned so that their positive electrode terminals 8 arealternately in different directions, and the cells 100 aligned in a rowmay be electrically connected to each other in series. Alternatively,the electrode terminals 21 a, 22 a as the positive electrode and thenegative electrode, and the signal terminal via which the signal forcontrolling charge and discharge of the cells 100 is input and outputare not necessarily incorporated into the battery assembly 200.

Alternatively, the battery assembly 200 may not be necessarilyaccommodated in the case 30. In this case, the battery assembly 200 isnot provided with the exhaust duct 50, but as described later, a batterymodule including a plurality of battery assemblies 200 is accommodatedin a case, so that an exhaust duct can be formed for the battery module.

The battery pack of the present invention is configured as a set of theplurality of battery modules, wherein the battery assembly 200 includingthe plurality of cells 100 aligned in a row is used as a unit, and eachbattery module is formed by aligning the plurality of battery assemblies200. The battery modules included in the battery pack include two typesof battery modules, that is, a first battery module including theplurality of battery assemblies 200 aligned in parallel, and a secondbattery module including the plurality of battery assemblies 200 alignedin series. The first battery module is combined with the second batterymodule to form the battery pack.

FIGS. 4A-4E are exploded perspective views schematically illustrating aconfiguration of a first battery module 300 of the present embodiment.FIG. 5 is a perspective view of the first battery module 300.

As illustrated in FIG. 4C, the plurality of battery assemblies (in thefigure, four battery assemblies) 200 are aligned in parallel to form thefirst battery module 300, where each battery assembly 200 includes aplurality of cells (in the figure, six cells) aligned in a row. Here,“aligned in parallel” means that the plurality of battery assemblies 200are aligned in Y direction perpendicular to X direction (row direction)in which the plurality of cells are aligned in a row.

In the first battery module 300, the positive electrodes and thenegative electrodes of the battery assemblies 200 aligned in parallelare electrically connected to each other in series. Specifically, theelectrode terminals 21 a as a positive electrode of the batteryassemblies 200 and the electrode terminals 22 a as a negative electrodeof the battery assemblies 200 are electrically connected to each otherin series, where the electrode terminals 21 a and the electrodeterminals 22 a are formed on the surface of the flat plate 20. Note thatthe negative electrode terminals (the bottom sections of the batterycases) of the cells 100 aligned in X direction are connected to eachother via the negative electrode bus bar 23, and are connected to thenegative electrode connection plate 22 formed on the flat plate 20 viathe conduction section 24 extending from a part of the negativeelectrode bus bar 23.

Here, instead of providing the flat plate 20 to each battery assembly200 as illustrated in FIG. 2, one flat plate 20 may be provided to thewhole first battery module 300. Alternatively, instead of accommodatingeach battery assembly 200 in the case 30, the whole first battery module300 may be accommodated in one case 30, and may be covered with a lid40. Alternatively, as illustrated in FIG. 5, an end section of the flatplate 20 may protrude from the outlet of the lid 40 to the outside, andthe electrode terminals 21 a, 22 a as a positive electrode and anegative electrode of the first battery module 300 may be exposed to theoutside. With this configuration, multiple ones of the first batterymodule 300 may be easily electrically connected to each other, or thefirst battery module 300 may be easily electrically connected to asecond battery module which will be described later.

FIG. 6A-6E are exploded perspective views schematically illustrating aconfiguration of a second battery module 400A of the present embodiment.FIG. 7 is a perspective view of the second battery module 400A.

As illustrated in FIG. 6C, the plurality of battery assemblies (in thefigure, two battery assemblies) 200 each including a plurality of cells(in the figure, six cells) aligned in a row are aligned in series toform a second battery module 400A. Here, “aligned in series” means thatthe plurality of battery assemblies 200 are aligned in a directionparallel to X direction (row direction) in which the plurality of cellsare aligned in a row.

In the second battery module 400A, the positive electrodes and thenegative electrodes of the battery assemblies 200 aligned in series areelectrically connected to each other in series. Specifically, thepositive electrode connection plates 21 and the negative electrodeconnection plates 22 of the battery assemblies 200 are electricallyconnected to each other in series via the electrode terminals 21 a, 22 aas a positive electrode and a negative electrode, where the positiveelectrode connection plates 21 and the negative electrode connectionplates 22 are formed on the surface of the flat plate 20. Moreover, thenegative electrode terminals (the bottom sections of the battery cases7) of the cells 100 of each battery assembly 200 are connected to eachother via the negative electrode bus bar 23, and are connected to thenegative electrode connection plate 22 formed on the flat plate 20 viathe conduction sections 24, 24 a extending from a part of the negativeelectrode bus bar 23.

Here, instead of providing the flat plate 20 to each battery assembly200 as illustrated in FIG. 2, one flat plate 20 may be provided to thewhole second battery module 400A. Alternatively, instead ofaccommodating each battery assembly 200 in the case 30, the whole secondbattery module 400A may be accommodated in one case 30, and may becovered with a lid 40. Alternatively, as illustrated in FIG. 7, an endsection of the flat plate 20 may protrude from the outlet of the lid 40to the outside, and the electrode terminals 21 a, 22 a as a positiveelectrode and a negative electrode the whole second battery module 400Amay be exposed to the outside. With this configuration, multiple ones ofthe second battery module 400A may be easily electrically connected toeach other, or the second battery module 400A may be easily electricallyconnected to the first battery module 300.

FIG. 8A-8D are exploded perspective views schematically illustrating aconfiguration of a second battery module of another embodiment. FIG. 9is a perspective view of a second battery module 400B of anotherembodiment.

In the present invention, the plurality of battery assemblies 200 arealigned in series to form the second battery module, where “aligned inseries” means, in addition to an alignment in which the plurality ofbattery assemblies 200 are aligned in a direction parallel to Xdirection (row direction) in which the plurality of cells are aligned ina row as illustrated in FIG. 6A-6E, an alignment in which the pluralityof battery assemblies (in the figure, two battery assemblies) 200 arealigned in an axial direction (Z direction) of the cells (cylindricalbatteries) 100 as illustrated in FIGS. 8A-8D. Specifically, the positiveelectrode connection plates 21 and the negative electrode connectionplates 22 of the battery assemblies 200 are electrically connected toeach other in series, where the positive electrode connection plates 21and the negative electrode connection plates 22 are formed on thesurface of the flat plate 20.

Here, instead of accommodating each battery assembly 200 in the case 30,the whole second battery module 400B may be accommodated in one case 30as illustrated in FIG. 9, and may be covered with a lid 40.Alternatively, an end section of the flat plate 20 may protrude from anoutlet of the lid 40 to the outside, and electrode terminals 21 a, 22 aas a positive electrode and a negative electrode of the whole secondbattery module 400B may be exposed to the outside. With thisconfiguration, multiple ones of the second battery module 400B may beeasily electrically connected to each other, or the second batterymodule 400B may be easily electrically connected to the first batterymodule 300 or the second battery module 400A.

Here, as illustrated in FIG. 5, the length L1, the height H1, and thewidth W1 of the external size of the first battery module 300 includingthe plurality of the battery assemblies 200 aligned in parallel dependon the product of the diameter of the cell (cylindrical battery) and thenumber of the cells aligned in a row in the battery assembly 200, on theheight of the cell in an axial direction, and on the product of thediameter of the cell and the number of the battery assemblies 200aligned in parallel in the first battery module 300, respectively.

Moreover, as illustrated in FIG. 7, the length L2, the height H2, andthe width W2 of the external size of the second battery module 400Aincluding the plurality of battery assemblies 200 aligned in seriesdepend on the product of the diameter of the cell (cylindrical battery),the number of the cells aligned in a row in the battery assembly 200,and the number of the battery assemblies 200 aligned in series in thesecond battery module 400A, on the height of the cell in an axialdirection, and on the diameter of the cell, respectively.

Moreover, as illustrated in 9, the length L3, the height H3, and thewidth W3 of the external size of the second battery module 400Bincluding the plurality of battery assemblies 200 aligned in seriesdepend on the product of the diameter of the cell (cylindrical battery)and the number of the cells aligned in a row in the battery assembly200, on the product of the height of the cell in an axial direction, andthe number of the battery assemblies 200 aligned in series in the secondbattery module 400B, and on the diameter of the cell, respectively.

That is, the minimum widths W2, W3 of the external sizes of the secondbattery modules 400A, 400B including the plurality of battery assemblies200 aligned in series match the minimum width (diameter of thecylindrical battery) of the cell (cylindrical battery) included in thebattery assembly 200. By contrast, the minimum width W1 of the externalsize of the first battery module 300 including the plurality of batteryassemblies 200 aligned in parallel varies depending on the number ofbattery assemblies 200 aligned in parallel, where the minimum width W1is at least the product of the minimum width of the cell and the numberof battery assemblies 200. Therefore, it is possible to widen thedifference between the minimum width of the external size of the firstbattery module 300 and the minimum widths of the external sizes of thesecond battery modules 400A, 400B. Thus, when the first battery module300 is mounted in a wide space, and the second battery modules 400A,400B are mounted in a narrow space, it is possible to increase theflexibility in mounting the battery pack in a limited space. Moreover,in forming the first battery module 300 and the second battery modules400A, 400B, the battery assembly 200 including a plurality of cellsaligned in a row is used as a unit, and thus the battery modules can beeasily formed.

FIG. 10 is a view schematically illustrating an example in which abattery pack including a plurality of battery modules is mounted on avehicle. In a relatively wide space under a rear seat, the first batterymodule 300 is disposed with the H1 being in a vertical direction, and ina narrow space under a floor between a front seat and the rear seat, thesecond battery module 400A is disposed with the minimum width W2 beingin the vertical direction, so that the battery modules can beefficiently disposed in the limited space.

Note that to allow an output of a predetermined voltage and capacitance,the battery pack of the present invention may be formed by accordinglycombining two types of battery modules having different external sizes(the first battery module 300 and the second battery modules 400A,400B), and the number of the battery modules 300, 400A, 400B, and howthe battery modules 300, 400A, 400B are aligned may be accordinglyselected depending on the size of a space in which the battery pack ismounted.

FIGS. 11A, 11B are perspective views illustrating an example combinationof the first battery modules 300 and the second battery modules 400B. InFIG. 11A, the plurality of first battery modules (in the figure, eightfirst battery modules) 300 are arranged in parallel in a relatively widespace, and the second battery modules 400B are arranged in parallel andin series (in the figure, three by three second battery modules 400B arearranged) in a narrow space. Note that some of the second batterymodules 400B may be stacked in two layers if there is enough space.

Alternatively, as illustrated in FIG. 11B, in addition to arranging thesecond battery modules 400B in the narrow space, the plurality of firstbattery modules (in the figure, eight first battery modules) 300 may bearranged in parallel in a relatively wide space, and in the remainingspace, the plurality of second battery modules (in the figure, threesecond battery modules) 400B may be arranged.

Here, as illustrated in FIGS. 11A, 11B, in the battery pack in which thefirst battery modules 300 are combined with the second battery modules400B, the axial direction of the cells in the battery assemblies 200included in the first battery modules 300 is orthogonal to the axialdirection of the cells in the battery assemblies included in the secondbattery modules 400B.

Moreover, the number of battery assemblies 200 aligned in parallel inthe first battery module 300 is not limited, and thus the number ofbattery assemblies 200 included in the first battery module 300 isgreater than the number of battery assemblies 200 included in the secondbattery module 400B.

In the above description, the present invention has been described withreference to the preferable embodiments, but the description is notintended to limit the invention, and of course, various modificationscan be made. For example, in the above embodiment, the example in whichthe battery assemblies 200 included in the first battery module 300, thesecond battery modules 400A, 400B are electrically connected to eachother in series has been described, but the battery assemblies 200 maybe electrically connected to each other in parallel. Although the cell100 is a cylindrical battery in the embodiments, the cell 100 may be arectangular battery. Alternatively, types of the cell are notparticularly limited, and for example, a lithium-ion battery, anickel-hydrogen battery, or the like may be used.

INDUSTRIAL APPLICABILITY

The present invention is useful as power sources for driving vehicles,electric motorcycles, electric play equipment, or the like.

DESCRIPTION OF REFERENCE CHARACTERS

-   -   1 Positive Electrode    -   2 Negative Electrode    -   3 Separator    -   4 Electrode Group    -   5 Positive Electrode Lead    -   6 Negative Electrode Lead    -   7 Battery Case    -   8 Terminal Board (Positive Electrode Terminal)    -   8 a Opening Portion    -   9, 10 Insulating Plate    -   11 Gasket    -   12 Filter    -   12 a Through Hole    -   13 Inner Cap    -   13 a Through Hole    -   14 Valve    -   20 Flat Plate    -   20 a Opening    -   21 Positive Electrode Connection Plate    -   21 a, 22 a Electrode Terminal    -   21 b Opening    -   22 Negative Electrode Connection Plate    -   23 Negative Electrode Bus Bar    -   24 Conduction Section    -   30 Case    -   40 Lid    -   40 a Outlet    -   50 Exhaust Duct    -   100 Cell    -   200 Battery Assembly    -   300 First Battery Module    -   400A, 400B Second Battery Module

1.-11. (canceled)
 12. A plurality of battery modules each including aplurality of cells aligned and accommodated in a case, wherein a batteryassembly including a plurality of cells electrically connected to eachother in parallel is used as a unit, and each battery module is formedby aligning multiple ones of the battery assembly, the battery modulesincludes a first battery module in which the battery assemblies arealigned in parallel, and a second battery module in which the batteryassemblies are aligned in series, the first battery module and thesecond battery module are combined with each other to form the batterypack, each cell has an opening portion through which gas generated inthe cell is exhausted to the outside, each battery assembly furtherincludes an exhaust duct in communication with the opening portion ofeach cell, the exhaust duct includes a flat plate disposed at one sideof the plurality of cells, the opening portions of the cells are incommunication with the exhaust duct via through holes formed in the flatplate, and on the flat plate, interconnects connected to electrodesections of the cells are formed.
 13. The battery pack of claim 12,wherein the opening portion of each cell is formed in an electrodeterminal of the cell
 14. The battery pack of claim 12, wherein eachbattery assembly includes an electrode terminal as a positive electrode,and an electrode terminal as a negative electrode, and a signal terminalvia which a signal for controlling charge and discharge of the cells isinput and output.
 15. The battery pack of claim 14, wherein in the firstbattery module, the electrode terminals as the positive electrodes andthe negative electrodes of the battery assemblies aligned in parallelare electrically connected to each other in series, and in the secondbattery module, the electrode terminals as the positive electrodes andthe negative electrodes of the battery assemblies aligned in series areelectrically connected to each other in series.
 16. The battery pack ofclaim 12, wherein the flat plate is arranged in close contact with anend section of each cell, and the exhaust duct is partitioned in asealed state with respect to the plurality of cells.
 17. The batterypack of claim 12, wherein the flat plate is formed as a circuit board,interconnects are formed on the circuit board, and the interconnects areconnected to the electrode terminals as the positive electrodes and thenegative electrodes, and the signal terminal of each battery assembly.18. The battery pack of claim 12, wherein the cells are cylindricalbatteries, in the first battery module, the battery assemblies arealigned in parallel in a direction perpendicular to a row direction ofthe plurality of cells aligned in a row, and in the second batterymodule, the battery assemblies are aligned in series in a directionparallel to the row direction of the cells or in an axial direction ofthe cells which are the cylindrical batteries.
 19. The battery pack ofclaim 18, wherein the axial direction of the cells in the batteryassemblies included in the first battery module is orthogonal to theaxial direction of the cells in the battery assemblies in the secondbattery module.
 20. The battery pack of claim 12, wherein the number ofthe battery assemblies included in the first battery module is greaterthan the number of the battery assemblies included in the second batterymodule.